On the left, four through-hole USB-C connectors laid out on a purple cutting mat. On the right, a teardown picture shows that there's neither resistors nor CC connections inside such a connector, resulting in consequences described in the article.

The USB-C Connectors You Never Knew You Wanted To Avoid

February 20, 2022 by Arya Voronova 24 Comments

On Tech Twitter, some people are known for Their Thing – for example, [A13 (@sad_electronics)], (when they’re not busy designing electronics), searches the net to find outstanding parts to marvel at. A good portion of the parts that they find are outstanding for all the wrong reasons. Today, that’s a through-hole two-pin USB Type-C socket. Observing the cheap tech we get from China (or the UK!), you might conclude that two 5.1K pulldown resistors are very hard to add to a product – this socket makes it literally impossible.

We’ve seen two-pin THT MicroUSB sockets before, sometimes used for hobbyist kits. This one, however, goes against the main requirement of Type-C connectors – sink (Type-C-powered) devices having pulldowns on CC pins, and source devices (PSUs and host ports) having pull up resistors to VBUS. As disassembly shows, this connector has neither of these nor the capability for you to add anything, as the CC pins are physically not present. If you use this port to make a USB-C-powered device, a Type-C-compliant PSU will not give it power. If you try to make a Type-C PSU with it, a compliant device shall (rightfully!) refuse to charge from it. The only thing this port is good for is when a device using it is bundled with a USB-A to USB-C cable – actively setting back whatever progress Type-C connectors managed to make.

As much as USB Type-C basics are straightforward, manufacturers get it wrong on the regular – back in 2016, a wrong cable could kill your $1.5k MacBook. Nowadays, we might only need to mod a device with a pair of 5.1K resistors every now and then. We can only hope that the new EU laws will force devices to get it right and stop ruining the convenience for everyone, so we can finally enjoy what was promised to us. Hackers have been making more and more devices with USB-C ports, and even retrofitting iPhones here and there. If you wanted to get into mischief territory and abuse the extended capabilities of new tech, you could even make a device that enumerates in different ways if you flip the cable, or make a “BGA on an FPC” dongle that is fully hidden inside a Type-C cable end!

When Battery Rebuilds Go Wrong: Understanding BMSs, Spot Welders, And Safety

February 16, 2022 by Ryan Flowers 41 Comments

Batteries are amazing. Batteries are horrible. Batteries are a necessary evil in today’s world of portable everything. If you’re reading this sentence, even if it’s not on a mobile device, somewhere there is a battery involved. They’re that ubiquitous. There’s another thing batteries are: Expensive! And at $350 each for a specialized battery, [Linus] of Linus Tech Tips decided to take battery repair into his own hands.

Rather than do a quick how-to video about putting new cells in an old enclosure, [Linus] does a deep dive into the equipment, skills, and safety measures needed when dealing with Lithium Ion cells. And if you watch the video through, you’ll even get to see those safety measures put to good use!

The real meat of the video comes toward the end however, with its explanation of the different Battery Management Systems (BMS), and a discussion of the difficulty of doing battery repair correctly and safely. Lastly, the video covers something a bit more sinister: Batteries that are made to resist being repaired with new cells; DRM for batteries, so to speak.

Overall we found the video informative, and we hope you do too. You might also enjoy this peek into the chemistry behind your favorite battery types.

Continue reading “When Battery Rebuilds Go Wrong: Understanding BMSs, Spot Welders, And Safety” →

How To Spot A Fake Op-Amp

February 5, 2022 by Jenny List 21 Comments

We’re all aware that there are plenty of fake components to be found if you’re prepared to look in the right places, and that perhaps too-good-to-be-true chip offers on auction sites might turn out to have markings which rub off to reveal something completely different underneath. [IMSAI Guy] saw a batch of OP-07 laser-trimmed op-amps at a bargain price, so picked them up for an investigation. You can take a look at the video below the break.

A perfect op-amp has a zero volt output when both of its inputs are at the same voltage, but in practice no real device approaches this level of perfection. It’s referred to as the offset voltage, and for instrumentation work where a low offset voltage is important there are parts such as the OP-07 which have each been adjusted using a laser to trim their components for the lowest offset. This process is expensive, so naturally so are genuine OP-07s.

Identifying real versus fake op-amps in this case is as simple as hooking the chip up as a unity gain non-inverting amplifier and measuring the voltage on the output (we can’t help a tinge of envy at that Keithley 2015 THD multimeter!), from which measurement the fakes should be clearly visible. First up are some 741s with their > 1 mV offsets (though an outlier 741 had a 40μV offset) to show what a cheap op-amp could be expected to do, then we see the OP-07s. Immediately with an offset of > 1.2 mV we can tell that they’re fake, which as he admits for the price is hardly a surprise. Meanwhile we’ll keep an eye out for Korean-made 741s like the outlier low-offset device.

If you’re interested by op-amp internals may we suggest a look at the first IC op-amp, meanwhile this isn’t the first fake chip we’ve seen.

Continue reading “How To Spot A Fake Op-Amp” →

Planar PCB Coils As An Alternative To Winding Transformers

January 29, 2022 by Jenny List 35 Comments

Those readers who have experimented with winding their own inductors will know that it’s not an easy task, and when those inductors are handling high voltages it can be especially tricky to maintain adequate insulation between layers of windings. [Open Frime TV] has a video addressing this in a novel way, by creating the windings for a switch-mode power supply transformer using stacked PCB coils instead of wire (Russian language; you’ll have to enable YouTube’s subtitle auto-translation).

The video below the break makes for a handy primer on PCB coil construction, reminding the viewer that the turns need all to lie in the same direction as well as the importance of insulation between windings. There’s a discussion of the properties of a PCB coil in relation to the switching frequency, and once the transformer has been assembled, we see it hooked up to a power supply board for a test. What happens next may be familiar to seasoned transformer-winders; nothing works, and the transformer gets hot. In making the PCB he’s left some copper on each board which amounts to a shorted turn — cutting these allows the transformer to work perfectly.

This technique might not be the solution to all transformer woes, but makes for an interesting option if your work takes you in the direction of winding transformers. If PCB coils take your interest, how about a Tesla coil using them?

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Upgrading A Soviet Calculator With A Modern CPU

January 27, 2022 by Robin Kearey 17 Comments

Today’s supply chain issues can make it hard to buy microcontrollers, or really any kind of semiconductor. But for those keeping retrocomputers alive, this problem has always existed: ancient components might have been out of production for decades, with a dwindling supply of second-hand parts or “new old stock” as the only option. If a rare CPU breaks, you might have no option but to replace the entire computer.

[Piotr Patek] ran into this issue when he obtained an Elektronika MK-85 programmable calculator with a broken CPU. Unable to find a replacement, he decided instead to build a pin-compatible CPU unit based on an STM32 microcontroller. Of course no modern CPU is pin-compatible with a Soviet design from the 1980s, so [Piotr] had to design a small interposer PCB to match the original pinout. This also gave him enough space to add an efficient DC/DC converter chip that generates the 2.5 V supply for the STM32.

As for the software, [Piotr] managed to port the original BASIC interpreter, which was written in PDP-11 assembly, to a modern equivalent written in C. While he was at it, he fixed a few bugs that had been sitting there for about 35 years. The updated CPU also allows the MK-85 to run circles around its contemporary siblings: [Piotr] timed it to be about thirty times faster than the original chip, while using a comparable amount of power.

If you also happen to have an MK-85 with a dodgy CPU, you’ll be pleased to find that the schematics and source code to [Piotr]’s modification are all available on his blog. This is probably the first calculator CPU update we’ve seen, although we’ve featured other ancient calculators updated with new firmware, and some completely new calculator designs based on classic hardware.

Thanks for the tip, [cmholm]!

555 Teardown Isn’t Just A Good Time, It’s To Die For

January 25, 2022 by Ryan Flowers 10 Comments

It seems only appropriate that hot on the heels of the conclusion of Hackaday’s 555 Timer Contest that [Ken Shirriff] posts a silicon die teardown of an early version of a hacker’s favorite chip, the 555.

Starting with a mystery chip from January 1973, [Eric Schlaepfer] painstakingly sanded down the package to reveal the die, which he deemed to be a 555 timer. Why didn’t they know it was a 555 timer to start? Because the package was not marked with “555” but rather some other marks that you can see in the blog post.

In addition to a great explanation of how the 555 works in general, [Ken] has taken a microscopic look at the 555 die itself. The schematic of a 555 is easily available, and [Ken] identifies not just sections of the die but individual components. He goes further yet by explaining how the PNP and NPN resistors are constructed in silicon. There’s also a nice and juicy bit of insight into the resistors in the IC, but we won’t spoil it here.

Be sure to show your love for the winners of the 555 contest, or at the very least check out the project that took the stop spot: a giant sized 555 that you don’t need a microscope to see inside of.

Remoticon 2021 // Debra Ansell Connects PCB In Ways You Didn’t Expect

January 20, 2022 by Elliot Williams 21 Comments

“LEDs improve everything.” Words to live by. Most everything that Debra Ansell of [GeekMomProjects] makes is bright, bold, and blinky. But if you’re looking for a simple string of WS2812s, you’re barking up the wrong tree. In the last few years, Debra has been making larger and more complicated assemblies, and that has meant diving into the mechanical design of modular PCBs. In the process Debra has come up with some great techniques that you’ll be able to use in your own builds, which she shared with us in a presentation during the 2021 Hackaday Remoticon.

She starts off with a quick overview of the state of play in PCB art, specifically of the style that she’s into these days: three dimensional constructions where the physical PCB itself is a sculptural element of the project. She’s crossing that with the popular triangle-style wall hanging sculpture, and her own fascination with “inner glow” — side-illuminated acrylic diffusers. Then she starts taking us down the path of creating her own wall art in detail, and this is where you need to listen up. Continue reading “Remoticon 2021 // Debra Ansell Connects PCB In Ways You Didn’t Expect” →